A government vaccine advisory panel has voted 14-1 that all adults 65 and older should receive the tetanus, diphtheria, and acellular pertussis (Tdap) vaccine.

A government vaccine advisory panel voted 14-to-1 on Wednesday that all adults 65 and older -- not just those who come into contact with infants -- should receive the tetanus, diphtheria, and acellular pertussis (Tdap) vaccine.

The vote by the CDC's Advisory Committee on Immunization Practices (ACIP) effectively establishes a recommendation of "universal" Tdap vaccination for all patients ages 19 and up.

Currently, Tdap is recommended in a single booster dose every 10 years for adults ages 19 to 64, and in those 65 and older who are likely to come in contact with infants younger than 12 months, such as grandparents and healthcare workers.

Boostrix is the only Tdap vaccine approved for use in the 65 and older group, but Adacel -- which isn't specifically approved for older patients -- can be used if that's what's in stock, according to the committee.

Carol Baker, MD, chair of ACIP, said the recommendation is intended to prevent providers from missing an opportunity to vaccinate.

Some panelists and alternate members worried, however, that the preference for one vaccine over the other spelled out in the guidance may confuse clinicians, especially if there are questions of Medicare coverage.

Specifically, the guidance states that the "approved Tdap vaccine ... should be used," although a dose of Adacel "is considered valid" and clinicians may "administer the vaccine that they have available."

The final language, due in the near future, should "take into account things that would confuse clinicians," Baker said.

Wednesday's ACIP decision was made following presentations demonstrating the cost efficacy, safety, and effectiveness of Tdap vaccination.

Anna Acosta, MD, of the CDC, said that cost-efficacy analyses by her agency revealed that cost per quality-adjusted life-year (QALY) gained rose as the incidence of disease increased.

Shanthy Krishnarajah, head of U.S. health outcomes for GlaxoSmithKline, maker of Boostrix, presented similar cost-efficacy data, noting that the cost per QALY gained fell below $50,000 at an incidence greater than 110 cases per 100,000 population.

However, estimating the incidence of pertussis in the U.S. is problematic, said Thomas Clark, MD, of the CDC.

Clark reported preliminary incidence of 15,000 cases in 2011, which is likely to be 20% to 25% higher when finalized, he said, but other research -- particularly from foreign countries -- suggests those numbers may be far higher.

Acosta said they're likely to be 100-fold higher, and Jennifer Liang, MD, of the CDC, said the work group concluded that both analyses show a "modest cost per QALY saved."

But ACIP member Jeffrey Duchin, MD, of the University of Washington in Seattle -- who cast the lone dissenting vote -- said the estimated efficacy levels used in the GSK study were troubling, noting that even in sensitivity analyses, 77% to 90% efficacy isn't a large enough range to show considerable differences.

"I hope you can convince me that these vaccines will be effective in the elderly population," he said.

Other panelists and attendees were concerned about a lack of immunogenicity data in older patients. Wayde Weston, director of clinical and medical affairs for U.S. vaccines at GSK, said although the company is collecting this data for patients ages 19 to 64, it's not doing so for those over 65.

ACIP member Michael Marcy, MD, of the University of Southern California, emphasized that the company should be collecting such data on this population.

Overall, Clark said, incidence is probably a bigger driver of cost efficacy than immunogenicity, noting that in adolescents, acellular pertussis vaccination is highly effective initially, but involves a "modest but immediate waning of immunity."

When asked why Boostrix was approved for patients 65 and up and Adacel was not, Wellington Sun, MD, director of vaccines and related product applications for the FDA, said the latter didn't prove noninferior to infant dosing data in terms of increasing antibody concentrations.

But data from foreign countries in which Adacel is used more widely has shown that the vaccine is effective in older populations, Acosta said.

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